The present invention relates generally to heating and heat maintenance apparatus for storage batteries, and, in particular, to an improved apparatus for heating and for maintaining temperatures in such storage batteries in high efficiency operating ranges regardless of extremely low ambient air temperatures.
As is well known in the automotive art, internal combustion engines, particularly diesels, are extremely hard to start in colder climates, such as the northern United States of America, during the winter months. This is due primarily to a combination of three factors precipitated by the cold weather. They are, the extreme thickening of engine lubricants, the lessened volatility of fuel mixtures, and the reduced cranking power of engine-starter storage batteries.
The design of a storage battery allows it to store the heat required for maximum output of cold cranking amps. In severe cold and especially in prolonged sub-zero temperatures a natural heat loss takes place and that is when the alternator, by itself, which is limited in its delivery of adequate compensation, cannot in the process of charging the battery deliver the necessary heat energy to maintain the battery's cranking capacity. It is well documented in the storage battery art that the reserve capacity, or cranking power of lead-acid storage batteries is reduced substantially by lower temperatures This drop is roughly 0.64% per degree Fahrenheit in the range of about 90.degree. F. to about -30.degree. F. or roughly 0.36% per degree Centigrade in the range of about 32.degree. C. to about -34.degree. C.
There have been many attempts to solve cold weather starting problems by engine "add-on" devices. The most common example of such an "add-on" device is the type of electric heater which heats various parts of the engine, oil, and fuel. Such electric heater units must be plugged into outlets continuously to be effective. Some electric warmers are also available for batteries. All of these plug-in heaters convert high grade energy into low grade heat and they cannot function if external electrical power is not available.
Other types of temperature-sustaining apparatus known in the storage-battery art require complex siphoning systems as taught by U.S. Pat. No. 2,399,942 to M. Resek, or relatively expensive systems having insulated containers, thermal regulation valves and related components as taught by U.S. Pat. No. 3,110,633 to W. D. Bachmann. Such systems have the further drawback of being extremely difficult to retrofit onto a vehicle having a standard factory-installed cooling system.
The present invention avoids the problems and complexities inherent in the aforedescribed prior art, and provides a novel and improved storage battery apparatus which maintains high efficiency and is easily adapted or retrofitted to vehicles having a system for circulating liquid coolant. Further, the present invention is compatible with existing devices, such as conventional tank heating equipment. It is also recognized that the present invention increases battery charging efficiency and, therefore, use of the present invention may result in the additional benefit of increased gas mileage.